1. Field of the Invention
This invention relates to an electronic musical instrument in which there are provided in a single manual keyboard two voicing blocks which have a certain keyboard space interval therebetween and at least one of which generates a multiple tone corresponding to keys being depressed, whereby it is possible to perform, with the single manual keyboard alone, results which are similar to that produce using a plurality of keyboards. By voicing blocks it is meant a block for generating tone signals such as that of the melody, chord, or base. Generally, these are respectively provided by separate independent upper, lower and pedal keyboards.
2. Description of the Prior Art
In the past, in order to play solo (melody), chord (accompaniment) and base (low-frequency range) tones, it has been necessary to use keyboards which were each independent voicing blocks, that is, upper, lower and pedal keyboards. In order that the keyboards may be partly used in common, use has been made of such methods as shown in FIGS. 1A, 1B and 1C. In FIG. 1A, the chord or solo part of one keyboard is fixedly interlocked with the base part at the positions of certain keys. With this method, however, the frequency range of the base tone is limited. In FIG. 1B, chord tones are outputted by depression of keys in parallel from tone sources respectively connected to the keys, and as the base or solo tone, the highest or lowest tone is derived from each tone source. This method has the defect that whenever the key is depressed, the highest and lowest tones are detected and the base and solo tones are produced concurrently with the chord tone. In the case of a synthesizer, as shown in FIG. 1C, the chord tones are similarly outputted in parallel by depression of keys, but the base tone (accampaniment) is produced by obtaining the highest or lowest pitch determining voltage by depressing a tap of a frequency divider connected to a constant-current source and applying it via an anti-log (-log) circuit to a voltage-controlled oscillator. In this case, the keyboards cannot be used in common.